Starch serves a crucial role in autotrophic organisms as a storage form of glucose. During photosynthesis, excess glucose is converted into starch, a polysaccharide composed of glucose units, which acts as a long-term energy reservoir. This storage polysaccharide is found in various parts of autotrophic organisms, such as roots, tubers, and seeds. When energy is needed, starch is broken down through enzymatic processes into individual glucose molecules, which can then undergo cellular respiration to produce ATP, providing the necessary energy for growth, reproduction, and metabolic activities in times when photosynthesis may not be actively occurring.